Processes for forming semiconductor devices on a substrate such as a silicon wafer often include one or more steps referred to as “planarization”. During planarization, a substrate is polished using a slurry in order to remove a top layer of material from the substrate and/or to produce a smooth uniform surface on the substrate. After planarization, it is customary to clean the substrate in a conventional cleaning device such as a megasonic cleaning tank.
It has been proposed to use a highly dilute surfactant solution as a fluid in a megasonic cleaning tank and/or as a fluid that is occasionally introduced into the megasonic tank as a “spike” to compensate for fluid loss due to evaporation or the like. However, conventional dilution apparatuses, in which a chemistry to be diluted and a dilutant are simultaneously flowed into a storage tank, may not operate with sufficient precision to reliably bring about a desired degree of dilution.